J/ApJ/703/614 UV star-forming regions in M31 (Kang+, 2009)
An ultraviolet study of star-forming regions in M31. Kang Y., Bianchi L., Rey S.-C. <Astrophys. J., 703, 614-627 (2009)> =2009ApJ...703..614K
ADC_Keywords: Photometry, ultraviolet ; Galaxies, nearby ; YSOs Keywords: galaxies: evolution - galaxies: individual (M31) - galaxies: star clusters - galaxies: structure - stars: early-type - ultraviolet: galaxies - ultraviolet: stars Abstract: We present a comprehensive study of star-forming (SF) regions in the nearest large spiral galaxy M31. We use Galaxy Evolution Explorer (GALEX) far-UV (1344-1786Å, FUV) and near-UV (1771-2831Å, NUV) imaging to detect young massive stars and trace the recent star formation across the galaxy. The FUV and NUV flux measurements of the SF regions, combined with ground-based data for estimating the reddening by interstellar dust from the massive stars they contain, are used to derive their ages and masses. The GALEX imaging, combining deep sensitivity and coverage of the entire galaxy, provides a complete picture of the recent star formation in M31 and its variation with environment throughout the galaxy. The FUV and NUV measurements are sensitive to detect stellar populations younger than a few hundred Myr. We detected 894 SF regions, with size ≥1600pc2 above an average FUV flux limit of ∼26ABmag/arcsecond2, over the whole 26kpc (radius) galaxy disk. We derive the star formation history of M31 within this time span. The star formation rate (SFR) from the youngest UV sources (age ≤10Myr) is comparable to that derived from Hα, as expected. Description: We considered 20 fields from the GALEX fourth data release (GR4). The GR4 data are processed with a pipeline processing system inaugurated in late 2007. GALEX observed the disk region of M31 as part of the Nearby Galaxies Survey (NGS, Bianchi et al. 2003lgal.conf...10B). Finally, we selected seven GALEX fields covering the entire disk region (see Figure 1). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 153 894 The UV detected SF regions in M31.
See also: J/ApJS/192/6 : A GALEX UV imaging survey of nearby galaxies (Lee+, 2011) J/MNRAS/399/728 : UV-bright sources behind M31 halo (Fittingoff+, 2009) J/ApJS/173/643 : GALEX UV photometry of M31 Globular Clusters (Rey+, 2007) J/ApJS/173/185 : GALEX ultraviolet atlas of nearby galaxies (Gil de Paz+, 2007) http://galex.stsci.edu/GR4/ : GALEX GR4/GR5 data release home page Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- ID [1003/7092] Object identification (<[KBR2009] NNNN> in Simbad) 6- 14 F9.6 deg RAdeg Right Ascension in decimal degrees (J2000) 16- 24 F9.6 deg DEdeg Declination in decimal degrees (J2000) 26- 31 F6.3 mag FUVmag GALEX FUV (1344-1786Å) band AB magnitude 33- 37 F5.3 mag e_FUVmag Uncertainty in FUVmag 39- 44 F6.3 mag NUVmag GALEX NUV (1771-2831Å) band AB magnitude 46- 50 F5.3 mag e_NUVmag Uncertainty in NUVmag 52- 55 F4.2 mag E(B-V) Reddening 57- 63 F7.1 arcsec2 Area Region area 65- 69 F5.1 Myr Age.02 ?=-99 Age for Z=0.02 and MW dust type (1) 71- 75 F5.1 Myr b_Age.02 ?=-99 Minimum Age.0.02 (1) 77- 81 F5.1 Myr B_Age.02 ?=-99 Maximum Age.0.02 (1) 83- 90 E8.2 Msun M.02 ?=-9.9 Mass for Z=0.02 and MW dust type (1) 92- 99 E8.2 Msun b_M.02 ?=-9.9 Minimum M.0.02 (1) 101-108 E8.2 Msun B_M.02 ?=-9.9 Maximum M.0.02 (1) 110-114 F5.1 Myr Age.05 ?=-99 Age for Z=0.05 and MW dust type (1) 116-120 F5.1 Myr b_Age.05 ?=-99 Minimum Age.0.05 (1) 122-126 F5.1 Myr B_Age.05 ?=-99 Maximum Age.0.05 (1) 128-135 E8.2 Msun M.05 ?=-9.9 Mass for Z=0.05 and MW dust type (1) 137-144 E8.2 Msun b_M.05 ?=-9.9 Minimum M.0.05 (1) 146-153 E8.2 Msun B_M.05 ?=-9.9 Maximum M.0.05 (1)
Note (1): The computations assumed a Milky Way type of interstellar reddening (Rv=3.1) and 2 different values of the metallicity Z=0.02 and Z=0.05. Values of "-99.0" and "-9.9e+01" indicate cases where the observed color is outside the range of model colors at all ages.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 20-Oct-2011
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